And he expects interest from the United States, where political speech compilations are "big business".

Mr Dale also anticipates a visit from the current Conservative leader, Michael Howard, who he says has already bought "Thatcher-related products" from the politics store.

Margaret Thatcher: The Great Speeches, due out next month, includes serious speeches and some "bonus material", including the former premier's appearance in a Yes Minister sketch and the mixing of her words and acid house music.

Lady Thatcher's speeches became part of the political landscape from the late 1970s through to her ousting as prime minister in 1990.

Power

"Her style of speaking developed over the years and she did become a much more powerful, more eloquent speaker," Mr Dale told BBC Radio 4's Today programme.

"She wasn't a natural orator. When she was first in government in the early Seventies she had a very clipped speech, and she obviously had some elocution lessons.

"But as she got into power, her power of speaking increased, and she got the self-confidence which politicians get once they get into power."

Many of her best-known quotes are phrases rather than speeches, such as the "No, no, no" she threw back to proposals from Jacques Delors, then president of the European Commission.

'Frit'

Or when she turned to her own Grantham roots for a dialect word to accuse Labour's Denis Healey of being afraid of a general election, saying he was "frit".

Party conferences were an opportunity for set-piece attacks, and these included "You turn if you want to, the lady's not for turning" in 1980, when she was under pressure to change economic direction.

In the case of her "dead parrot" conference speech, attacking the Liberal Democrats in 1990, Mr Dale says that Mrs Thatcher had never heard of the Monty Python references being parodied, but she was still able to deliver the joke and get a laugh.

Iron lady

Other phrases have become associated with the Thatcher era, such as being "the Iron Lady". This phrase was coined by a Soviet newspaper - and in 1976, Mrs Thatcher said that she was ready to accept it as a compliment.

Lady Thatcher can also lay claim to presenting one of the first political warnings against global warming.

Back in 1988, in a speech to the Royal Society, she raised the then little recognised problem of a "global heat trap which could lead to climatic instability".

In the same year, she delivered a key tract for Eurosceptics, as her Bruges Speech called for a less integrationist approach to the European Union.

Music producer Charles Bailey, who has mixed versions of the speeches of Labour veteran Tony Benn says that Lady Thatcher's delivery lends itself to this type of CD presentation - and it is "right on the button and sexy".